With its good spanning capacity and whole structural stress performance, the prestressed concrete box girder is widely used in modern large-span bridge structures. But, if the construction of box girder prefabricated control is inappropriate, cracks will appear easily, thereby the structure stability and durability will be greatly influenced. Through analysis of concrete box girder constituent materials, pouring temperature, construction process, and according to correlative concrete anti-cracking theories and analysis, there comes the prestressed concrete box girder crack preventative measures and repairing technic.